What created the big bang?

Variants of this question are;

What existed before the big bang?

Can something come from nothing?

Where did the universe come from?

A new theory of the multiverse may hold all the answers!

© 2026 Kieron Conway - All rights reserved.

A theory that may answer the impossible questions

At long last, we may be on the verge of having answers to these most fundamental questions, thanks to cosmologist Laura Mersini-Houghton. 

She has developed predictions based on the theory of the multiverse, which could one day be verified, possibly with help that came from Stephen Hawking before his sad demise.

Setting the scene – Our Universe

We have a beautiful theory of cosmology that states that our observable universe may once have been compressed into a region far smaller than an atom.

Suddenly, this minute object began a period of super-inflation where it grew at a rate faster than the speed of light.

As the universe expanded, it cooled and slowed down as particles and photons formed, creating a dense, opaque soup of expanding hot-plasma.

As the universe continued to expand and cool, the particles separated and formed atoms and the universe became transparent and photons began to travel in the CMB (Cosmic Microwave Background).

Gravity started to pull atoms together until the first suns were created, then galaxies. And so it continues.

This theory of how the universe started from the beginning of time (T=0) is supported by a wide range of observational evidence.

(If you want to know more about the evolution of the universe, Part 2 of A Journey into Modern Physics will give you the low-down).

The story of the birth of our evolution is a beautiful, verified and elegant theory with a single flaw.

The Flaw

It is possible using entropy and statistics to calculate the probability of our universe coming into existence, on its own, from a single embryonic patch of intense energy with an incredibly low entropy (maximum state of order).

Don't forget that we are talking about all the energy of the universe compressed into something roughly the size of a proton.

Entropy is a measure of a system's state of disorder and the universe's entropy, taken as a whole, is constantly increasing.

In local areas of the universe, entropy does decrease as gravity condenses matter to form stars and galaxies but overall, the entropy of the universe increases and it is unlikely to start decreasing in the future.

Even the Victorians appreciated this when they came up with the concept of entropy.

The probability of our universe having such low entropy at the beginning of time (T=0) is extraordinarily unlikely, according to current estimates.

This is a massive flaw in an otherwise beautiful theory of cosmic inflation leading to the universe of today.

But is our universe a one-off?

A Revolution in Quantum Physics

In the 1950s, as quantum physics was establishing itself, the general belief was that our universe was unique.

It was also believed that when a quantum object's wave function collapsed because of a measurement or an interaction with a piece of apparatus, the result entered the classical world and so we lived in a classical universe.

At this time, a student was completing his PhD thesis with a radical idea.

Steve Everett (1930 – 1982) couldn't agree with the general consensus that the quantum nature of objects was abandoned when an interaction occurred.

He felt that you either have a classical universe, or you have a quantum universe, but not a mixture.

He developed a theory, where all the outcomes of all quantum wave functions collapsing were played out in an almost infinite number of universes.

In this fully quantum paradigm, the multiverse was born. This was revolutionary talk!

It was at such odds with the belief that there was a single universe that Everett was asked not to publish his thesis for risk of antagonising some of the great names in quantum physics.

Although it was published, it was largely ignored.

So, he abandoned the world of physics and became a very disillusioned individual.

30 years on

In the 1980s, one of Mersini-Houghton's colleagues, Bryce Dewitt (1923 - 2004), had always had faith in Everett's work and as the editor of a physics journal he published Everett's thesis in full to a wide audience.

Dewitt also renamed the “multiverse theory” to the “many worlds interpretation of quantum physics”, in which everything that can happen does.

Suddenly, cosmologist's started taking the theory of the multiverse seriously as it explained so many unexplained things in quantum physics and this included the birth of our universe.

In a multiverse, our lone universe becomes one of an almost infinite number of universes, where the probability of it starting with such a low entropy becomes a statistical variant rather than a practical impossibility.

A Theory of Everything

Some of the best minds in physics, including Albert Einstein (1879 - 1955), had for decades been trying to develop a theory of everything.

In this theory, all four of the fundamental forces of nature would be united and gravity would have a quantum explanation.

It was felt that from a theory of everything, the origin of a single unique-universe would manifest itself.

This is how string theory started out, but ironically did the opposite.

The Energy-Rich Landscape of String Theory

First of all, if our embryonic universe was no bigger than a proton, holding the entire energy of the universe, it must have been a quantum object.

Just suppose that there is some higher state in which quantum universes are being created all the time.

Before our universe's birth, imagine an energy-rich landscape, populated by quantum waves rolling across the energy troughs and peaks.

Every now and again, a wave-function falls into a trough and collapses, resulting in many entangled embryonic-universes forming.

Each such quantum universe goes through cosmic inflation, like ours did, and in the process quantum effects become effectively unobservable, and the universe itself becomes classical.

This loss of observable quantum properties is known as decoherence.

So, instead of supporting the concept of our universe being unique, the many versions of string theory suggest a large landscape of possible universes.

In these universes, everything that can happen does, just like Hugh Everett proposed in the 1950s.

The legacy of detaching from other universes

Mersini-Houghton believes that if this process of our universe detaching itself from the entangled universes at its birth is correct, then there must be evidence of this in the temperature fluctuations of the CMB.

NASA launched probes, to provide detailed measurements of the temperature variations across space embedded in the CMB, our snap-shot of the early universe.

These probes were; COBE (1989), WMAP (2001) and Planck (2009) leading to a very detailed map of the fluctuations across the CMB.

Mersini-Houghton established the complex mathematics to describe variations in the CMB resulting from decoherence.

She produced a set of predictions on how the temperature variations of the CMB would be affected by the decoherence of our universe.

She believes that her work may provide a methodology for proving the existence of a multiverse.

Current Status of Results

So far, there is no direct evidence to indicate that decoherence has caused anomalies in the CMB that cannot be explained by the current, leading model of the evolution of the universe known as the Lambda-CDM model.

On the other side of the coin, the multiverse has not been disproved by these measurements either.

The jury remains out.

Taming the Multiverse

Stephen Hawking (1942 - 2018) was never a great fan of the multiverse, but Mersini-Houghton began to convince him otherwise with her view of creation and how to prove its existence.

He and Thomas Hertog have built a simpler model of the multiverse and cosmic inflation, with a view to hunting for the impact of gravitational waves on the CMB and the large structures of the universe such as the cosmic web.

In this simpler multiverse, there are a finite number of universes rather than almost infinite members.

As an embryonic universe contains all the energy of that universe, it must be a monumental gravitational source and the act of decoupling from all the entangled universes must have generated disturbances in our universe and hopefully left their imprint.

The hunt is on for the scars left by decoherence, on our universe.

Any evidence gathered in the future from this work may support Laura Mersini's theory.

A Final Thought

You have to admit, the idea of a multiverse being involved in the creation of our universe and its ability to allow all quantum possibilities to be acted out across the multiverse is very appealing.

This is as close as we can get to explaining the birth of the universe as well as what existed before it was born and how it was born.

At present, it's only a theory.

We have to wait for possible verification that could tell us that our universe is not alone in the cosmos.

--

If you want to learn more about Laura Mersini-Houghton's work, here is a YouTube link to a lecture she gave to the Royal Institution: https://www.youtube.com/watch?v=GYVg50_w1UA

Liked this article? Check out:

modern-physics-journey.com 

where you can read all about an exciting new science series: A Journey into Modern Physics, available from Amazon and Rakuten Kobo on-line shops. (Some of the above article appears in this series).

Also, the web-site has an index of blog articles published to date, for easy access to an article that might interest you.